- 學位論文
高分子側鏈含咔唑、矽苯修飾咔唑或三苯胺基團之合成及其高分子發光二極體之應用
Synthesis and Characterization of Polymers with Alkyl Main Chain Pendent Carbazole, Arylsilane-Modified Carbazole or Triphenylamine Unit as Host for Polymer Light Emitting Diodes
摘要
本研究中，主要開發新穎高分子有機發光二極體的材料及其元件之製備。 在第一、二章中分別介紹OLED的原理及常用於OLED元件之材料介紹。 在第三章中，使用聚氨酯(urethane)做鏈結，以芴(fluorene)和三苯胺(triphenylamine)之功能性官能基基團製備具有電洞傳遞效果之聚氨基甲酸酯(polyurethane，PU)的電洞傳遞層材料。 為了使其具有較佳的元件表現，加入了2-(phosphonooxy)ethyl methacrylate (P2M)改善了電洞注入層材料(PEDOT:PSS)與PU的介面問題，使磷光發光元件的最大亮度達到9560 cd/m2，最大效率達到27.6 cd/A。 在第四章中，乃合成出烷基主鏈側鏈懸掛咔唑(carbazole)或三苯胺之高分子做為綠光磷光發光元件之主發光體，藉以了解咔唑與三苯胺作為主發光體在性質方面之影響。熱性質方面由於咔唑和三苯胺具有剛硬的結構，因此具有較高的玻璃轉移溫度和熱裂解溫度；光學性質方面，此類結構具有較短的共軛結構，因此具有較高的三重態能隙使能量可以有效將能量傳遞至客發光體；電化學研究發現，材料具有良好的電洞傳遞特性，能階匹配元件製作所需的材料；當元件摻混4 wt%的Ir(ppy)3，其最大亮度達15800 cd/m2，最大效率達到17.5 cd/A。在第五章中，透過自由基聚合反應，合成一系列側鏈含矽苯修飾咔唑均聚物，其中咔唑具有良好的電洞傳遞性質和較高的三重態能隙。矽苯基團具有中斷共軛使高分子三重態能隙提高的效果，且引入巨大的矽苯基團於高分子側鏈可抑制分子的堆疊避免客發光體因為自我聚集造成濃度焠熄的現象。藉由觀察材料的熱穩定性質、光學性質變化、電化學性質等，並製作有機電激發光元件，以探討材料的結構設計對元件發光效率的表現。由於咔唑和矽苯屬剛硬的結構，因此高分子皆有高的玻璃轉移溫度和熱裂解溫度，顯示材料有良好的熱穩定性質。高的三重態能隙使能量可以有效傳遞至客發光體，並藉由能量轉移實驗可以加以佐證。電化學研究發現，材料具有良好的電洞傳遞特性，能階匹配元件製作所需的材料。在元件製備方面，此類高分子具有高的三重態能階，因此可作為藍光元件之主發光體材料進而製備成白光元件。藍光電激發光元件以P1摻雜20 %的FIrpic和40 %的TRZ有最佳的表現，元件結構為ITO/PEDOT/P1:FIrpic 20 %:TRZ 40 %/Mg/Ag，最大亮度2460 cd/m2，最大效率為4.93 cd/A。在白光電激發光元件方面以P1為主發光體所製備的元件具有最佳表現，元件結構為ITO/PEDOT/P1:FIrpic 20 %:Ir(2-phq)2acac 0.4 %:TRZ 40 %/Mg/Ag，最大亮度為4000 cd/m2，最大效率為5.13 cd/A。
並列摘要
In this study, to development a series of novel materials in polymer light emitting diodes and to fabricate devices were been focused subject. In chapter 1 and chapter 2 were introduced the principle and common materials of OLED. In chapter 3, functionalized polyurethanes containing fluorene and triphenylamine-derived for hole-transporting material in PLED device. In order to enhance the performance of device, the 2-(phosphonooxy)ethyl methacrylate (P2M) was introduced to improve the surface between PEDOT:PSS and PU that leads to an extremely good performance of the phosphorescent PLED. In chapter 4, polymers with alkyl main chain pendent carbazole or triphenylamine unit as host for green emitterin phosphorescence PLED devices. All the polymers show good thermal stability with high glass transition temperature (Tg) and decomposition temperature (Td) due to their rigid structure. The optical properties, these polymers have a shorter conjugated length at side chain which will raise triple energy level in order to efficiently assist energy transfer to the guest. The electrochemical behaviors reveal that the energy levels of polymers match the material used in devices. The best electroluminescent performance is 15800 cd/m2 and 17.5 cd/A with doped 4wt% Ir(ppy)3. In chapter 5, by free radical polymerization, the series of carbazole-based polymeric host materials, containing arylsilane-modified and 3,6-disubstituted carbazole frameworks, respectively. Carbazole has good hole-transporting characteristic and high triplet energy gap. Arylsilane group could interrupt conjugation length and raise triplet energy level. The bulky arylsilane group could restrain polymer aggregation preventing guest self-quenching. The thermal stability, optical properties, electrochemical properties, and the electroluminescent performance are discussed. All the polymers show good thermal stability with high Tg and Td due to their rigid structure. The high triplet energy gap of polymers can efficiently assist energy transfer to the guest, and can be corroborated by the energy transfer experiments. The electrochemical behaviors reveal that the energy levels of polymers match the material used in devices. The best blue electroluminescent device is ITO/PEDOT/P1:FIrpic 20 %:TRZ 40 %/Mg/Ag which has maximum luminance 2460 cd/m2 and maximum current efficiency 4.93 cd/A. The best white electroluminescent device is ITO/PEDOT/P1:FIrpic 20 %:Ir(2-phq)2acac 0.4 %:TRZ 40 %/Mg/Ag which has maximum luminance 4000 cd/m2 and maximum current efficiency 5.13 cd/A .
參考文獻
延伸閱讀
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